Chromium Bicyclic Amidine Catalysts for Selective Ethylene Tetramerization
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Solution Overview
Problem
Existing catalyst systems for ethylene oligomerization, such as those based on metal complexes of pyridine bis-imines and α-diimine compounds, face challenges in providing efficient and selective production of alpha olefins, particularly in terms of controlling the formation of specific oligomers like 1-hexene and 1-octene.
Innovation Solution
A catalyst system comprising an N2-phosphinyl bicyclic amidine chromium salt complex or a chromium salt with an N2-phosphinyl bicyclic amidine, combined with an organoaluminum compound, is used to facilitate the oligomerization of ethylene, forming a catalyst system that enhances the production of targeted olefins like 1-hexene and 1-octene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing catalyst systems (metal complexes of pyridine bis-imines and α-diimine compounds) are used for ethylene oligomerization, then the production of alpha olefins can be achieved, but the selectivity for specific oligomers like 1-hexene and 1-octene is insufficient
Solution Approach 1:
The patent modifies the ligand structure parameters by introducing N2-phosphinyl bicyclic amidine complexes with specific structural features (bicyclic framework, phosphinyl groups at N2 positions). These parameter changes in the catalyst structure lead to improved selectivity for 1-hexene and 1-octene while maintaining high productivity, resolving the contradiction between selectivity and efficiency
Solution Approach 2:
The catalyst system employs a composite structure combining chromium metal center with N2-phosphinyl bicyclic amidine ligands, creating a composite catalytic system that achieves both high selectivity for specific oligomers and high reaction efficiency. The synergistic interaction between the metal center and the specially designed ligand framework enables simultaneous improvement of both selectivity and productivity
2Quantity of substance
If existing catalyst systems are used, then oligomerization can proceed, but the yield of desired products like 1-hexene and 1-octene is limited
Solution Approach 1:
By changing the structural parameters of the ligand to N2-phosphinyl bicyclic amidine configuration, the catalyst achieves higher yields of desired oligomers (1-hexene and 1-octene). The parameter optimization in the ligand design enhances product distribution toward target molecules without requiring complex multi-component systems
Solution Approach 2:
The patent extracts and isolates the key structural features necessary for high selectivity and yield (the N2-phosphinyl bicyclic amidine framework) from more complex existing systems. This extracted core structure maintains simplicity while achieving superior performance in terms of desired oligomer yield
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed catalyst system improves the selectivity and efficiency of ethylene oligomerization, effectively producing a higher yield of desired products like 1-hexene and 1-octene, addressing the limitations of existing technologies.
Implementation Method 1
catalyst system comprising an N2-phosphinyl bicyclic amidine chromium salt complex or a chromium salt with an N2-phosphinyl bicyclic amidine, combined with an organoaluminum compound, is used to facilitate the oligomerization of ethylene
Data Source
Figure 1
AI summary
The present disclosure relates to a catalyst system comprising i) (a) an N2-phosphinyl bicyclic amidine chromium salt or (b) a chromium salt and an N2-phosphinyl bicyclic amidine and ii) an organoaluminum compound. The present disclosure also relate to a process comprising: a) contacting i) ethylene; ii) a catalyst system comprising (a) an N2-phosphinyl bicyclic amidine chromium salt complex or (b) a chromium salt and an N2-phosphinyl bicyclic amidine; ii) an organoaluminum compound, and iii) optionally an organic reaction medium; and b) forming an oligomer product in a reaction zone.